RE: [EnergyPlus_Support] AHU with a DXcoil and variable air flow

To: "EnergyPlus_Support@xxxxxxxxxxxxxxx" <EnergyPlus_Support@xxxxxxxxxxxxxxx>

Subject: RE: [EnergyPlus_Support] AHU with a DXcoil and variable air flow

From: "Edward G. Lyon" <eglyon@xxxxxxx>

Date: Thu, 3 May 2012 16:23:10 +0000

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Thread-topic: [EnergyPlus_Support] AHU with a DXcoil and variable air flow

I don’t know if the Energy+ software/equipment will do this, but practically DX equipment has a narrower constraint on airflow variations. If your flow goes outside the boundaries of what the equipment is designed for, you risk either coil freezing or compressor overloads/damage. E+ will give you warnings about these deviations. Variable airflow systems typically use fluid coils as that configuration is more easily controlled without equipment risks.

Ned Lyon, P.E. (MA)
Staff Consultant

SIMPSON GUMPERTZ & HEGER
781.907.9000 main
781.907.9350 direct
781.907.9009 fax
www.sgh.com

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of joao.rosa83
Sent: Thursday, May 03, 2012 11:49 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] AHU with a DXcoil and variable air flow

Hello,

I'm trying to setup an AHU 100% Outside air with a DX coil and a variable air flow rate?

It is possible to use de unitary equipment "AirLoopHVAC:UnitaryHeatPumpAirToAir" with a Fan: VariableVolume ? I'm using the "AirLoopHVAC:UnitaryHeatPumpAirToAir" with a Fan:CostantVolume with Coils:DX:SingleSpeed and a AirTerminal:SingleDuct:VAV:HeatAndCool:NoReheat, but the OA remains constant.

The goal is to have a constant temperature at the exit of the AHU and change the mass flow according to the zones internal loads and the zone setpoint temperature.

Thanks for your help
João

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